This invention relates to apparatus and methods for lifting materials with a crane, and more particularly to a lifting apparatus that and positions a plurality of reinforcing bars into a vertical position ready for connecting into a reinforcing assembly for incorporation into a reinforced concrete structure.
In the production of reinforced concrete structures, vertical steel reinforcing bars (rebars) must be precisely positioned and connected to lower steel elements before the pouring forms enclose them. As an example, thirty feet long #11 rebars weight about 160 pounds each. To lift each one separately and hold it vertically while it is being connected to a lower steel element is very difficult and labor intensive. Connection to a lower steel element is generally by a threaded coupling, but may include swaging or welding, for example. A single structure may include hundreds or thousands of such rebars.